The invention relates to a storage rack having at least one shelf with a number of storage spaces for pallets arranged over top of each other, which are held in the storage spaces by vertical rack supports arranged at the face, and which can be horizontally removed from the storage spaces from the side. In order to remove the pallets from the storage spaces of the rack as well as for storing pallets in the storage spaces of the rack, a rack operating device is provided, which is arranged at the longitudinal side of the rack and which can approach each storage space.
Stored on the pallets of a generic storage rack are particularly sheet metal, circuit boards, and poles made from metal in order to provide material for steel wholesale in a sorted fashion and to remove it for commissioning purposes, supply it to a processing station (for example a machine saw or a sheet metal processing machine), and to store the remaining pieces of the material and/or the processed material back in the storage rack. For this purpose the rack operating device approaches the storage space in which the pallet with the requested material is being stored, removes said pallet via a manipulator arranged on the rack operating device laterally from said storage space, and moves the pallet to the lowermost storage space of the rack formed by a station cart. The rack operating device transfers the respective pallet to the station cart. The station cart itself can be moved horizontally out of the rack on a pair or rails, with the pair of rails leading out of the rack at the side of the lowermost storage space facing away from the rack operating device; when the rack operating device is arranged behind the rack the station cart can therefore drive out of it on its rails at the front of the rack.
The pallet that has left the rack on the station cart or the material located on said pallet is then usually fed in a transfer station to a processing machine, for example a desired piece is cut off the material, and the remaining piece of the material and/or the processed material is once more placed onto the station cart and/or onto the pallet located thereupon, and then the station cart is moved back to the rack and assumes the lowermost storage space. From here the rack operating device can remove the pallet again, bring it to the original or a different storage space allocated by a rack storage control, and store it there.
When sheet metal is stored in storage racks of the present type, fed via the station cart to sheet metal processing machines, such as flat bed—laser machines, it has proven advantageous to provide an upper cart as a second station cart in addition to the just described station cart. This upper cart has the same properties as the station cart, in principle, with it being arranged above the station cart in the rack and here also assuming a storage space. The station cart and the upper cart can be moved out of the rack and returned back into the rack independently in reference to each other, with one of the two, usually the station cart, being used as a supply cart to provide the material while the other cart, usually the upper cart, serves as the return cart to place the processed material back in the rack.
The presence of two independently operating carts in a storage rack of the present type causes some problems, though. In order to optimally utilize the given space the vertical rack supports forming the rack frame are distanced from each other only to such an extent that the pallets can just be horizontally moved sideways between the rack supports; the distance between the rack supports each arranged at the face is therefore equivalent to the length of the stored pallets plus a certain clearance to allow removing the pallets between the rack supports sideways out of the rack and/or to insert them therein. Due to the fact that the station cart removes entire pallets, also sideways out of the rack, it requires clear space on the rails along its entire traveling distance equivalent in its width approximately to the distance between the rack supports. Therefore, the upper cart cannot simply be moved on a second pair of rails similar to the station cart extending at the same height as the first pair of rails of the station cart, because the second pair of rails also had to extend into the rack and thus had to have a distance between the two rails smaller than the distance of the rail supports and thus also smaller than the extension of the pallets transported on the station cart. Supports of the upper cart by which it can be moved on the second pair of rails would therefore interfere with the station cart and hinder the station cart and the upper cart to be moved entirely independently from each other between the rack and the processing and/or commissioning station.
One approach to avoid this problem is to move the second pair of rails above the station cart, thus to elevate it. However, here any crossing of the traveling path of the upper cart is no longer possible; furthermore elevated rails form a disturbing edge for automatic supply installations, removing the material from the upper cart and particularly the station cart and feeding them to the processing station.
Another approach to avoid the described problem comprises arranging the rack supports further apart than usual so that the second pair of rails can be guided into the rack over a rail width larger than the length of the pallets. The upper cart can then be guided along rails arranged at the same height as the first pair of rails without the supports necessary here interfering the traveling path of the station cart. However, here it is not only required for the rack to be wider than actually necessary but additionally it is necessary to provide additional spacing elements at the rack supports in the area of the normal storage spaces, i.e. except for the storage spaces formed by the station cart and the upper cart, to allow holding the pallets; then the pallets cannot be held directly at the rack supports. In addition to increased space necessary this also results in increased material expenses; furthermore, when using this approach an existing storage rack cannot be retrofitted with an upper cart.